The present invention relates to gold alloys and, more particularly, to certain nickel/iron alloys of gold which, when heated as described herein, may display a visually observable increase in blue coloration.
In order to manufacture jewels and articles of gold, certain aesthetically desirable effects may be imparted to gold jewelry or other articles by using gold alloys having different colorations which make it possible to obtain a decorative effect.
For this purpose, one can use alloys having one component which confers a predominant color on the item. For instance, copper may be added to gold to produce a red-gold alloy, or palladium may be added in order to produce a grayish-gold alloy. Alternatively, desired coloration of the metal surface can be obtained, for example, by electrodeposition or by heat treatment.
German application DE-3641 228 Al discloses an alloy of gold, chromium, molybdenum, vanadium, carbon, tungsten and iron. The alloy presents an iridescent blue coloration after brief treatment with a flame.